Giving pregnant women the hormone progesterone can reduce their risk of premature delivery by one third, offering the first clear-cut way to head off this increasingly common and dangerous problem, a study found. Low birth weight and serious, sometimes deadly complications also occurred less often in babies whose mothers got the weekly injections, according to the study in a recent New England Journal of Medicine.

Doctors who treat high risk pregnancies and those who work in the fertility field have known for years that progesterone protects the baby and helps maintain the pregnancy (PRO GEST erone  --  means FOR Gestation).
Women who have had a spontaneous preterm delivery are at increased risk for preterm delivery in subsequent pregnancies. The results of several trials have suggested that 17 alpha-hydroxyprogesterone caproate (17P) may reduce the risk of preterm delivery.

One such trial was a double-blind, placebo-controlled study involving pregnant women with a documented history of spontaneous preterm delivery. The study established that treatment with 17P significantly reduced the risk of delivery at less than 37 weeks of gestation. Also, Infants of women treated with 17P had significantly lower rates of necrotizing enterocolitis, intraventricular hemorrhage, and need for supplemental oxygen.

The progesterone proved so effective that the study was halted early because it would have been unethical to keep giving some women a placebo.

The researchers concluded that weekly injections of 17P resulted in a substantial reduction in the rate of recurrent preterm delivery among women who were at particularly high risk for preterm delivery and reduced the likelihood of several complications in their infants.

Source Information
* Meis, P.J. . . . and A.M. Peaceman. 2003. Prevention of recurrent preterm delivery by 17 alpha-hydroxyprogesterone caproate. New England Journal of Medicine348(June 12):2379-2385.
* da Fonseca, E.B., et al. 2003. Prophylactic administration of progesterone by vaginal suppository to reduce the incidence of spontaneous preterm birth in women at increased risk: A randomized placebo-controlled double-blind study. American Journal of Obstetrics and Gynecology 188(February):419-424.
* Greene, M.F. 2003. Progesterone and preterm delivery—déjà vu all over again. New England Journal of Medicine 348(June 12):2453-2455.
* Johnson, J.W.C., et al. 1975. Efficacy of 17a-hydroxyprogesterone caproate in the prevention of premature labor. New England Journal of Medicine 293(Oct. 2):675-680.
* Yemini, M., et al. 1985. Prevention of premature labor by 17 alpha-hydroxyprogesterone caproate. American Journal of Obstetrics and Gynecology 151:574-577.